All-Solid-State Oxygen Ion Electrochemical Random-Access Memory for Neuromorphic Computing

Abstract

Artificial synapses based on electrochemical random-access memory (ECRAM) have emerged as an important component for neuromorphic chips because they are capable to execute simultaneous signal transmission and memory operations. However, existing ECRAM synapse surfers with compatibility and rapid memory loss issue due to highly reactive Li+ and H+ cationic species. Here, all-solid-state oxygen ion-based ECRAM (O-ECRAM) synapse, which shows linear weight update characteristics through multi-level nonvolatile analog conductance states is presented. Crucially, an O-ECRAM device delivering the highly stable, nonvolatile multi-level conductance states through reversibly controlling the O2- ion tunneling via oxygen vacancies in oxides heterostructure of ionically conducting Y2O3-stabilized ZrO2 electrolyte (YSZ) and electrically conducting WO3. The kinetic of O2- induced reversible phase transition in WO3 under YSZ electrolyte gating is triggered using X-ray photoelectron spectroscopy. Ionic conduction of O2- species through oxygen vacancies in YSZ electrolyte is traced by visualizing in situ conductive filament growth. Oxygen vacancy in YSZ electrolyte provides fast oxygen ion conduction, resulting in an analog switching in WO3 with a fast speed of 10 ms, high retention of more than 10(3) s, and excellent endurance up to 10(3) pulses. These benefits prove that the O-ECRAM device can be a potential candidate for developing neuromorphic hardware.